Returns a wrapper around func which calls func, with all its arguments and
keywords unmodified, using the default sys.displayhook. Since IPython
modifies sys.displayhook, it breaks the behavior of certain systems that
rely on the default behavior, notably doctest.

resets its global ‘master’ attribute to None, so that multiple uses of
the module interactively don’t produce cumulative reports.

Monkeypatches its core test runner method to protect it from IPython’s
modified displayhook. Doctest expects the default displayhook behavior
deep down, so our modification breaks it completely. For this reason, a
hard monkeypatch seems like a reasonable solution rather than asking
users to manually use a different doctest runner when under IPython.

Notes

As of Python 2.6.6, 2.7.1 and 3.2, this monkeypatching is no longer required.
doctest now takes care of resetting sys.displayhook itself. This function
remains for now in case anyone has to work with older versions, but it’s
no longer called during IPython startup.

This function used to reload doctest, but this has been disabled because
reloading doctest unconditionally can cause massive breakage of other
doctest-dependent modules already in memory, such as those for IPython’s
own testing system. The name wasn’t changed to avoid breaking people’s
code, but the reload call isn’t actually made anymore.